As physiotherapists working with geriatric populations, a common clinical frustration is the perceived variability in patient outcomes. When treating sarcopenia and dynapenia, we often encounter the hypothesis that certain older adults are simply “non-responders” to exercise therapy due to genetic factors or anabolic resistance. However, a compelling 2026 study published in PLoS One challenges this notion, suggesting that true physiological non-responders to heavy resistance exercise training (HReT) are exceptionally rare.
Quantifying Response Variability in Older Men
The study, conducted by Soendenbroe and colleagues, performed a secondary analysis on a randomized controlled trial involving 58 healthy older men with a mean age of 72. The participants were randomized into either a sedentary control group or a heavy resistance exercise (EX) group. The EX group engaged in thrice-weekly training sessions for 16 weeks.
The researchers aimed to quantify inter-individual variability across five key physiological outcomes: maximal voluntary contraction (MVC) strength, rate of force development (RFD), quadriceps cross-sectional area (qCSA), and type I and II myofibre cross-sectional area (fCSA). By utilizing the standard deviation of individual responses (SDIR), the team sought to classify participants into categories ranging from “Poor” to “Excellent” responders.
The Verdict on Non-Responders
The aggregate data demonstrated significant improvements in the exercise group compared to the sedentary group. After 16 weeks, the exercise group saw an average increase of 19% in MVC and a substantial 58% increase in RFD. Hypertrophy was also evident, with increases in quadriceps CSA and Type II fiber CSA.
However, the most clinically relevant finding lies in the individual response analysis. The study found that 82% of the participants were classified as either Robust or Excellent responders. Conversely, only 5% were classified as “Poor” responders. This data strongly suggests that the concept of a “non-responder” in the context of geriatric resistance training is largely a myth. While magnitude varies, the physiological signal from heavy loading almost universally provokes a positive adaptation.
Clinical Implications for Physiotherapists
Interestingly, the study noted that training compliance and 1RM progression did not fully explain the variability in results. However, lower baseline levels were associated with greater relative improvements, reinforcing the importance of targeting deconditioned individuals who have the most to gain.
For the clinician, these findings support the implementation of Heavy Resistance Exercise Training as the unparalleled first-line strategy for mitigating age-related muscle loss. The fear that a patient will not respond to therapy should not deter the prescription of high-load exercise. If a patient is not progressing, the issue is statistically unlikely to be biological non-response; rather, clinicians should reassess programming variables such as intensity, volume, or recovery strategies.
References
Soendenbroe, C., Andersen, J. L., Heisterberg, M. F., Kjaer, M., & Mackey, A. L. (2026). Heavy resistance exercise training in older men: A responder and inter-individual variability analysis. PLoS One. https://pubmed.ncbi.nlm.nih.gov/41563970/
